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Science & Mathematics

The Museum's collections hold thousands of objects related to chemistry, biology, physics, astronomy, and other sciences. Instruments range from early American telescopes to lasers. Rare glassware and other artifacts from the laboratory of Joseph Priestley, the discoverer of oxygen, are among the scientific treasures here. A Gilbert chemistry set of about 1937 and other objects testify to the pleasures of amateur science. Artifacts also help illuminate the social and political history of biology and the roles of women and minorities in science.

The mathematics collection holds artifacts from slide rules and flash cards to code-breaking equipment. More than 1,000 models demonstrate some of the problems and principles of mathematics, and 80 abstract paintings by illustrator and cartoonist Crockett Johnson show his visual interpretations of mathematical theorems.

The Omicron Ellipsograph Model 17 was manufactured by the Omicron Company of Glendale, CA, in the 1950s. An oval shape, the ellipse is one of the four conic sections, the others being the circle, the parabola, and the hyperbola. Ellipses are important curves used in the mathematical sciences. For example, the planets follow elliptical orbits around the sun. Ellipses are required in surveying, engineering, architectural, and machine drawings for two main reasons. First, any circle viewed at an angle will appear to be an ellipse. Second, ellipses were common architectural elements, often used in ceilings, staircases, and windows, and needed to be rendered accurately in drawings. Several types of drawing devices that produce ellipses, called ellipsographs or elliptographs, were developed and patented in the late 19th and early 20th centuries. The U.S. Army purchased several of this device for use in surveying and mapping.

The Omicron Ellipsograph is not an elliptic trammel like many of the other ellipsographs in the Smithsonian’s collections. This ellipsograph is a linkage, in particular a Stephenson type III linkage. A linkage is a mechanical device made of rigid bars connected by hinges or pivot points that move in such a way as to produce smooth mathematical curves. The most common types of linkages are used to draw true straight lines. See the Kinematic Models in the Smithsonian’s online collections for examples of other linkages.

In this ellipsograph, a metal bar is attached to two sliding brackets. One is on the stationary bar that runs horizontally across the device and is the major axis of the ellipse. The other sliding bracket is attached to a curved arm. A pencil is inserted through the hole at the top end of the bar. As the pencil is moved, the linkage articulates at five pivot points (the two adjustable sliders and three pivots as seen in the image). This constrains the pencil to move in an elliptic arc. Unlike the elliptic trammel, only half an ellipse can be drawn with this device, making it a semi-elliptic trammel. It can be turned 180 degrees to draw the other half of the ellipse. Although this device cannot draw a complete ellipse in one motion, it does have the advantage of being able to draw very small ellipses. By adjusting the distance between the two slider brackets, the eccentricity of the ellipse can be changed. Eccentricity is a number between zero and one that describes how circular an ellipse is. By moving the slider brackets closer together, the eccentricity of the ellipse is reduced, creating a more circular ellipse. As the brackets are moved farther apart, the eccentricity is increased and a more elongated ellipse is produced.

Several demonstrations of how an elliptic trammel works are available online. Comparing the slider motion of the elliptical trammel and the linkage ellipsograph highlights the similarities of the motion of these two ellipsographs. Both devices constrain the motion of the sliders so that as one moves inward on a straight line, the other slider moves outward on a straight line perpendicular to the first. Thus both types of ellipsographs produce an elliptic curve using the same mathematical theory, but incorporating different physical configurations.

The Omicron Ellipsograph is made of aluminium and steel on an acrylic base. The base is 18.5 cm by 8.5 cm (7 1/4 in by 3 3/8 in). The top bar is 18 cm (7 in) long. The whole linkage rests on the central pivot directly above the company logo. It can draw ellipses with major axes up to 12 inches long.

This vertical chamber for gel electrophoresis was made in 1974 for the Stanley Cohen lab at Stanford University. Gel electrophoresis was one of the most important tools Cohen and Boyer used to analyze the effects of restriction enzymes on plasmids. The technique allows a way to visualize and isolate molecules by separating them out according to their length using an electrical current (for power supply see object 1987.0757.27).

For more information on the Cohen/Boyer experiments with recombinant DNA see object 1987.0757.01

This power supply was used in the Stanley Cohen lab at Stanford University to run an electrical current through a vertical chamber for gel electrophoresis (see object 1987.0757.14). Gel electrophoresis was one of the most important tools Cohen and Boyer used to analyze the effects of restriction enzymes on plasmids. The technique allows a way to visualize molecules by separating them out according to their length using an electrical current.

For more information on the Cohen/Boyer experiments with recombinant DNA see object 1987.0757.01

This refractometer was used in Stanley Cohen’s lab at Stanford University in his research on recombinant DNA. Refractometers measure how light changes velocity as it passes through a substance. This change is known as the refractive index and it is dependent on the composition of the substance being measured. In the Cohen lab, this refractometer was one of several techniques used to provide evidence that he and his research team had created a recombinant DNA molecule containing DNA from both a bacterium and a frog.

To conduct the analysis, Cohen separated out the molecule he assumed to be recombinant DNA and measured its refractive index. The index for the molecule fell between the known values for frog DNA and bacterial DNA, suggesting that the unknown DNA molecule was a mixture of the two.

For more information on the Cohen/Boyer experiments with recombinant DNA see object 1987.0757.01

This UV light box was used in the lab of Stanley Cohen at Stanford University in his research on recombinant DNA. UV light boxes are used to help visualize results from of DNA and RNA analysis through gel electrophoresis. Molecules subjected to gel electrophoresis create a pattern of bands on a gel medium as they move. Scientists can interpret the pattern to obtain the results of the analysis. However, because the bands of molecules are naturally colorless, they must be dyed to be made visible. Dyes that fluoresce under UV radiation are commonly used. This UV light box was used to provide illumination behind the dyed bands, causing them to fluoresce so that they could be photographed and interpreted.

For more information on the Cohen/Boyer experiments with recombinant DNA see object 1987.0757.01

This fermenter was used at Genentech during the early 1980s to grow recombinant bacteria for the production of proteins to be used as medicine. Recombinant bacteria have been genetically altered in a way that makes them capable of producing proteins they wouldn’t naturally produce.

To begin the production process, this fifteen-liter stainless steel tank was seeded with a small sample of recombinant bacteria. The tank provided an environment that encourages bacteria to grow and multiply by controlling the steam, water, temperature, and pressure in the tank. Below the tank is an agitation mechanism, that “stirred” the bacteria, ensuring even access to resources. When the bacteria grew to a number where they filled the tank, they were transferred to a larger fermentation tank as part of an industrial scale-up process.

This object is part of a set-up for vertical gel electrophoresis. Gel electrophoresis is a technique that uses the electrical charges of molecules to separate them by their length. It is often used to analyze DNA fragments.

This set-up was cobbled together by scientists in the lab at Genentech, a biotechnology company, in the late 1970s and used through the 1980s. Its different components were purchased from several suppliers in the San Francisco Bay area and assembled together with binder clips. Although gel electrophoresis set-ups were available for purchase at the time, scientists found their own set-ups to be more reliable and easier to troubleshoot.

Because of its long length, this device was particularly useful for sequencing stretches of synthetic DNA created in the lab. A long length allows for greater resolution between molecular fragments, an important consideration in sequencing efforts.

This object is part of a set-up for vertical gel electrophoresis. Gel electrophoresis is a technique that uses the electrical charges of molecules to separate them by their length. It is often used to analyze DNA fragments.

This set-up was cobbled together by scientists in the lab at Genentech, a biotechnology company, in the late 1970s and used through the 1980s. Its different components were purchased from several suppliers in the San Francisco Bay area and assembled together with binder clips.

Because of its short length, this device was primarily used to perform preparative and analytical DNA work rather than sequencing, which requires a long length to provide greater resolution.

This plastic chamber was part of a set-up for a vertical gel electrophoresis chamber used in the lab at Genentech, a biotechnology company, in the late 1970s and early 1980s. Gel electrophoresis is a technique that uses the electrical charges of molecule to separate them by their length. It is often used to analyze DNA fragments. “Yansura,” the name of one of the scientists who used the set-up, is etched on one side of the chamber.

This plastic chamber was part of a set-up for a vertical gel electrophoresis chamber used in the lab at Genentech, a biotechnology company, in the late 1970s and early 1980s. Gel electrophoresis is a technique that uses the electrical charges of molecules to separate them by their length. It is often used to analyze DNA fragments.